1. Field of the Invention
The present invention relates to a test system for radio frequency IC devices, particularly radio frequency IC devices used for radio frequency identification (RFID) systems, and to a method of manufacturing radio frequency IC devices using the test system.
2. Description of the Related Art
Recently, there have been rapid advances in technology regarding contactless identification media (e.g., contactless ID cards) called radio frequency identification (RFID) media, which are used in various areas. Such an RFID medium has a specific range of communication with a reader/writer defined in accordance with its performance, and thus, there is a demand for improved communication measurement and yield.
A typical existing manufacturing process for radio frequency IC devices used for RFID systems includes forming antenna coils on a film base and mounting radio frequency IC chips thereon such that a predetermined number of the devices are formed on the film base having a predetermined size. Then, the characteristics of each of the radio frequency IC devices are measured to determine whether it is a good product or not before it becomes a stand alone product.
However, since the test described above is performed at a stage before the radio frequency IC device is formed as a stand alone device, responses to a communication signal from an RFID reader/writer are received such that a desired response from a test piece, i.e., a test object, is mixed with responses from neighboring radio frequency IC devices. In this case, in addition to a problem of receiving unreliable data, there arises a problem in which, when the test object is a bad test piece, data from radio frequency IC devices that are near the bad test piece being measured may be received and may cause the bad test piece to be determined to be a good product, even though the test piece is not a good product. This allows bad products to be shipped.
Japanese Unexamined Patent Application Publication NO. 2003-99721 and Japanese Unexamined Patent Application Publication NO. 2003-76947 disclose test systems in which, in order to avoid cross talk caused by radio frequency IC devices in the vicinity of a test object, a shield member having an opening is provided between a radio frequency IC device to be tested and the antenna of a measurement system, where the opening enables the antenna of the measurement system to face only the radio frequency IC device to be tested. With this structure, responses to a communication signal from an RFID reader/writer are received such that a response from the radio frequency IC device to be tested is prevented from being mixed with responses from the neighboring radio frequency IC devices.
A test object in such test systems includes at least an antenna and a radio frequency IC chip. Since the antenna portion of such a radio frequency IC device is very large, radio frequency IC devices on a conveyor belt of the test system must be spaced apart from one another by a distance about the size of one radio frequency IC device. This causes a problem in which testing of one radio frequency IC device requires an increased amount of movement of the conveyor belt and test time, which leads to increased test costs.
Furthermore, a radio frequency IC device that includes at least an antenna and a radio frequency IC chip requires a process of mounting a radio frequency IC chip on a film that has antenna electrodes formed thereon, and a process of electrically connecting the antenna electrodes and the radio frequency IC chip. These manufacturing processes occupy the majority of the manufacturing time, and therefore, significantly increase manufacturing costs.